Agrihan (Agrigan)

Location: 18.8N, 145.7E

Elevation: 965m (3,166 ft.)

Area 47 sq. km

Island type: high volcanic cone, radially dissected

Agrigan is a stratovolcano with a small caldera at its summit. The volcano forms an island about 4 miles (7 km) in diameter. It is largest and tallest volcano in the Northern Mariana Islands. Agrigan is made of basalt and lesser amounts of andesite. A single known historic eruption in 1917 threw blocks up to about 1 yard (1-m) in diameter as far as 3 miles (5-km) from the vent. About 10 feet (3-m) of ash fell on a coastal village. Deformation measurements made on Agrigan in 1992 revealed no significant changes since the volcano was first measured in 1990. In August of 1990, an increase in fumarole activity was observed on the cone within the caldera. No earthquakes were felt . The island's nine residents were evacuated. No eruption occurred. The southwest and west flank of Agrigan shows deeply dissected slopes. The lower slopes are covered with palm trees, and the upper slopes are covered with swordgrass, making this area unpassable. Agrihan is situated 206 nautical miles north of Saipan and has an area of 11.4 square miles. This volcano has gentle slopes near the shore on the southeast and southwest sides with the crater entrance on the north side. The remainder of the island consists of steep slopes and deep gorges. The coast is rocky and steep with a landing beach only on the southwest coast.

 

Natural threats: cyclones, volcano.

Human impact: small resident population; coconuts, lower slopes cultivated.

Ecosystems: rain forest in ravines, Miscanthus grasslands on upper slopes.

Special features: dormant volcano; forest of conservation interest, summit unexplored botanically.

Species of conservation interest
Birds : 
    Megapodius laperouse laperouse (Marianas Megapode) group endemic subspecies, Rare (RDB); 
    Gallinula chloropus guami (Marianas Gallinule or Common Moorhen) group endemic subspecies, Pagan, Saipan, Tinian, Guam, Rare (RDB), local status unknown.

Ratings
Natural conservation status 1. 
Ecosystem richness 1. 
Species richness 1. 
Economic pressure 0. 
Human threat 1. 
Natural vulnerability 2. 
Practicality of conservation action 2. 
Reliability of data 2. 
Human impact 1. 
Conservation importance 15
 

Uracas  Maug   Ascuncion  Agrigan   Pagan  Alamagan   Guguan  Sarigan   Anatahan  Medinilla

Saipan  Tinian   Aguihan  Rota   Guam

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